A trolling motor is a self-contained unit that includes an electric motor, propeller and controls, and is affixed to a boat, either at the bow or stern. Trolling motors are often used by anglers, such as bass fishermen, who want their boat to slowly move around an area, or to maintain their position, while they cast their lures. A trolling motor is usually a secondary means of propulsion mounted on the transom alongside the watercraft's primary outboard motor. However, a trolling motor may be the primary source of propulsion for smaller watercraft, such as canoes and kayaks, and on lakes where the use of a gasoline-powered engine is prohibited.
FIG. 1 illustrates a prior art clamp mounted trolling motor that is adapted for removably mounting to a watercraft. The motor 10 is attached to a propeller 12 by propeller shaft (See Ref. 70 in FIG. 3C) which extends from the back portion of the motor housing 24. A skeg 14, which is a rudder or fin for the motor 10, extends from the bottom of the motor housing 24 and a shaft 16 extends from the top of the motor housing 24. A clamp 18 is provided for clamping the assembly onto the watercraft and for adjusting the position of the shaft 16. At the top of the shaft 16 is the tiller 20 and controls 22 for steering and operating the assembly, respectively. Other trolling motors are adapted for permanent mounting on the bow of a watercraft, such as a bass boat. These motors replace the clamp 18 of the motor 10 of FIG. 1 with a mounting assembly and often include a foot pedal that allows the motor to be controlled by the user's foot. One of ordinary skill in the art will recognize that many variations may be made on this basic design for a trolling motor and the present invention should not be seen as being limited to any specific style of trolling motor.
All trolling motor users are familiar with the perpetual problem of grasses, weeds, lily pads, or other aquatic vegetation, getting wound around the propeller or shaft of trolling motors. Following this, in the best of scenarios, the trolling motor loses efficiency. If this vegetation gets too wound around the propeller, it becomes necessary to stop the motor, remove it from the water, and remove the vegetation. Not only is this a nuisance, but as the propeller and/or skeg may be sharp, the user is in danger of cutting himself during the removal process. In addition, damage may be caused to the seals around the propeller shaft, which keep water from coming into contact with the electric motor, thus necessitating major repair of the trolling motor. In other circumstances, the stuck vegetation may cause the propeller to stop rotating completely; sometimes called “shorting” the trolling motor. Such a short may cause temporary or permanent damage to the motor. In addition, if the trolling motor is the watercraft's primary outboard motor, then the trolling motor user is stuck in place. If the trolling motor is the watercraft's secondary outboard motor, the user may be forced to use the primary gasoline-powered motor, which will likely end his fishing for the day, and may be illegal, depending on where he is. Therefore there is a need to prevent the buildup of aquatic vegetation around the propeller of trolling motors.
This need was the object of U.S. Pat. No. 4,911,664 to Gremillion. This invention discloses a weed cutting and shredding attachment for an electric trolling motor including a sharpened cutting blade oriented with the sharp edge thereof adjacent to the path of the movement of the leading edge of the propeller blades on an electric trolling motor together with a mounting structure for effectively mounting the cutting element from the trolling motor. The attachment includes a cutting element or blade, provided with a bracket structure for detachably and removably securing the attachment to the trolling motor.
Although this invention discloses one manner in which to address the problem, this device had several drawbacks that prevented it from being commercially successful. First, this attachment extended outward from the skeg and forward of the intersection between the propeller and the motor housing, which renders it ineffective at cutting vegetation that has wrapped itself around the rear portion of the propeller. Second, because its sharp blade extends outward from the skeg, it creates a serious safety hazard. Third, the design requires that the device be mechanically fastened to the skeg, preferably by drilling and tapping a hole in the skeg and screwing it in place. This drilling and tapping is undesirable. It often causes the motor's warranty to be voided and, should the mechanical fastener loosen, it can contact the propeller, causing damage and, potentially shorting. In addition, as the mechanical fastener loosens, it renders the device ineffective and prone to loss. Fourth, as the attachment protrudes out and down between the propeller and skeg, the cutting element may simply end up being another protrusion around which vegetation may wind, which is especially true as the cutting element dulls. Finally, the device is not adapted for manufacturing as part of the motor itself, which relegates the device to the aftermarket. Therefore, there is ample room for improvement over this invention.
Another attempt to address the problem of the winding vegetation is to add a sharpened blade, such as a metal blade, to the skeg of the trolling motor, so that the skeg is extended to be quite close to the propeller, and also sharpened. Although this model may have some success, it also has its drawbacks. First, it will affect the watercraft's steering by making the rudder effectively larger. The person steering the watercraft will have to accommodate himself to the change, as smaller moves may result in larger changes in direction. In addition, the attachment, which is usually secured with screws through the skeg will make the skeg less fluidly dynamic, again affecting the steering of the watercraft. Moreover, the sharp edge is a serious safety hazard and, as the sharp edge of the skeg attachment dulls, the attachment will only serve to decrease the space between the skeg and the propeller so that there is less space for vegetation to travel naturally therethrough, thus creating greater and more severe blockages.
Therefore, there is a need a device that is effective at cutting vegetation that has wrapped itself around the rear portion of the propeller, that does not extend outward from the skeg, that does not creates a serious safety hazard, that does not need be mechanically fastened to the skeg, that will not cause the motor's warranty to be voided, that will not be prone to contacting the propeller, that is not prone to loss, that may be integrated into the motor housing, and that will not result in the cutting element being another protrusion around which vegetation may wind.